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Everything below comes from the National Bee Unit’s wasp fact sheet (December 2024) unless said otherwise. It lists four measures that work: reduce the entrance, fit a robbing screen, be careful how you feed, and keep colonies strong. Sources are at the foot of the page.
When it happens
Wasp predation can start as early as July in a bad wasp year, though it usually becomes obvious in August. Numbers fall away in autumn, normally around late September. 1
So you have about eight weeks to get through. That is worth knowing, because this is a siege to survive rather than a problem to solve for good.
Seven UK wasp and hornet species will attack colonies. 1 The European hornet is one of them, and it is the one people panic about needlessly. It looks alarming, it is not aggressive, and it usually takes only a few bees.
Social wasps spend most of the summer feeding their young on flies, caterpillars and mosquitoes. They are a gardener’s friend for months before they become your problem. That is why the guidance is firm about not killing them wholesale.
1. Reduce the entrance
Insert entrance blocks in late summer, or as soon as you see wasps working the apiary. A smaller doorway is simply easier for the guard bees to hold. If robbing has already started, take it down to a single bee space.
Two variations on that are worth knowing, because both are named in the guidance and both are things you can make:
- A tube entrance. The NBU’s wording is that a small tube entrance “can be easier for bees to defend because it is challenging for the wasp to venture along the tube amongst the flow of bees”. 1 A wasp will not push up a tunnel against oncoming traffic.
- An underfloor entrance. These can be bought from suppliers or made at home, and they reduce the impact of heavy wasp predation. 1 The bees come up from below, which is a route wasps are much less inclined to work out.
Most hive types have an off-the-shelf version of one or the other - a WBC can be fitted with an underfloor door, a Flow hive comes with an entrance reducer that doubles as a mouse guard - and a strip of wood, or a block of sponge pushed into the gap, does the same job for nothing. Sponge has the advantage that you can pull a bit out or push a bit in as the colony’s strength changes.
From our own apiary. After a bad wasp year we adapted the entrance on one hive with a length of plastic cable trunking run across the front, open at both ends, so the bees come in from either side and a wasp has to find and then hold a corridor it cannot see down. That hive has given us the least trouble of any since.
Separately, several of our other hives are on underfloor entrances, and we reduce those to a couple of inches by pushing sponge into the gap; the WBC has a bought underfloor door. The sponge is the part worth copying - you can pull a bit out or push more in as the colony’s strength changes, and it costs pence. None of it is clever, and all of it worked better than anything we bought to solve the problem.
2. Fit a robbing screen
A robbing screen works by moving the real way in while leaving the old entrance visible. Wasps keep battering at the doorway they can see and fail to get through it, while the bees learn the new route quickly. You can buy them, or make one from a sheet of clear acetate scored and folded, or from a single panel of mesh. Pinned over the doorway it wants to be about a bee space high - 5 mm at most.
Put them on nucs as well as full colonies. A nuc is the most likely thing in your apiary to be robbed out. A Canadian escape cone set into a coffee tin lid is a cheap way to protect one. 1
3. Be careful how you feed
Spilled syrup or honey brings in wasps and sets your own bees robbing. Feed in the late evening when wasps and foragers are not flying, and clear up anything you spill straight away. Beekeeper reports - anecdotal, but consistent enough to be recorded in the guidance - are that feeding fondant rather than syrup reduces robbing 2, which makes sense: it is taken slowly and does not excite the colony.
There is more on strengths and timing in feeding for winter.
4. Keep colonies strong, and unite the weak ones
Strong colonies are the least likely to be attacked and the most likely to come through to spring, so uniting a small colony in late summer is doubly worthwhile. 3 Check thoroughly for disease first. Uniting a sick colony into a healthy one just hands the problem on, and if you see anything that looks like foulbrood, stop - that is notifiable, and there are things you must not do with those combs.
Two things not to do
Traps. Tempting, and the NBU is blunt: unlikely to be particularly effective, and a high risk of killing other native invertebrates. 1 They also do nothing about the nest. If you use them at all, keep them away from the hives and look at what is actually in them. One distinction worth making: a yellow-legged hornet monitoring trap is a different job - detection, so that a nest can be found and destroyed officially - and the bycatch warning applies there too.
The decoy hive. You will hear the suggestion that you move the bees into a clean hive and leave the old one with some comb to keep the wasps busy. It does not work, and leaving open combs standing in an apiary is a disease risk. Do not do it.
Telling robbing from a wasp attack
Both look like trouble at the entrance, and the fix is not quite the same, so watch for a minute first.
Wasps hover and dart. They work the sides and any crack rather than the front door, and they take an interest in your extractor and your tea as well as the hive.
Robbing bees come at the front in numbers, and you get real wrestling on the landing board, with bees locked together and falling off. Look on the floor and the ground in front. Wax flakes and chewed cappings mean comb is being torn open.
The hardware is much the same either way - a small entrance and a robbing screen help against both - but the follow-up is not. Wasps are seasonal, and the job is to hold the door until the season ends. Bees robbing bees has a cause in your apiary, and that cause is what you have to remove: a super left out, a spill, an open feeder, a long inspection in a dearth, or a colony too weak to defend itself and better united than propped up. Narrow the entrance to stop the bleeding, then find what started it.
While you are watching the entrance
Late summer and autumn is when yellow-legged hornet (previously Asian hornet) sightings are reported, and hawking at a hive entrance is exactly the behaviour to look for. The NBU gives the size difference: yellow-legged hornet workers are about 25 mm, European hornet workers about 30 mm. 1 Look for a mostly black abdomen with a yellow band on the fourth segment, yellow legs and an orange face. Report through the free Asian Hornet Watch app, the online form, or alertnonnative@ceh.ac.uk, with a photograph and the location. There is more detail in our guide to identifying and reporting one.
What to write down
Entrance behaviour is obvious at the time and forgotten by the next visit. “Being robbed, reduced entrance to one bee space, settled by the 25th” is the note that tells you next August which hive is chronically weak rather than unlucky, and which site attracts wasps every single year.
Where the hives sit, and how far apart, changes how much trouble you get: Choosing and laying out an apiary.
The two jobs that most often start a robbing war are taking the supers off and putting a feeder on. Both pages have the precautions that belong to them.
This guide is general information, not legal advice. Rules change - always check the current guidance on GOV.UK before relying on it.